Abrasion-proof reducing oil pipe of producing well

Abstract

The invention relates to the technical field of sleeve joints, and discloses an anti-wear producing well reducing oil pipe which comprises a reducing joint for connecting adjacent oil pipes, and an anti-friction shunting mechanism is arranged in the reducing joint; the antifriction flow dividing mechanism is composed of a flow dividing inner pipe and an aperture adjusting assembly, a plurality of optical fiber sensors are arranged between the flow dividing inner pipe and the liquid inlet end of the reducer union, the aperture adjusting assembly comprises a flexible inner wall film, double contraction cores and a tension spring piece, the double contraction cores are embedded in the liquid inlet end and the liquid outlet end of the flexible inner wall film in a spring shape, and the tension spring piece is connected with the flexible inner wall film. The adjacent ends are elastically connected through tension spring pieces; the antifriction flow dividing mechanism is arranged in the reducer union, abrasion of the oil pipe is effectively reduced, the service life is prolonged, and the optical fiber sensor arranged between the flow dividing inner pipe and the liquid inlet end of the reducer union can collect pressure and flow velocity parameters of liquid in real time.

Description

Technical Field

[0001] The present invention relates to the field of casing joints, and more specifically, it relates to a wear-resistant variable-diameter oil pipe for oil production wells. Background Art

[0002] With the continuous growth of global oil demand, the oil production industry is facing increasing production pressure and technical challenges. Among many oil production equipment, the oil pipe, as a key component connecting the oil reservoir and surface oil production facilities, its performance and service life have an important impact on oil production efficiency and cost. During the long-term use of traditional oil pipes for oil production wells, many problems are faced, such as wear of the pipe wall, corrosion, scaling, etc. These problems not only reduce the service life of the oil pipe, increase the maintenance and replacement costs, but also may lead to the interruption of oil production operations and affect the stable production of oil.

[0003] During oil production, the liquid flow velocity in the oil pipe is relatively fast, especially when mining oil reservoirs containing solid particles such as sand grains, the erosion wear of the solid particles on the pipe wall is particularly serious. The inner wall of the traditional oil pipe is usually a smooth metal surface, lacking effective protection measures, resulting in the gradual thinning of the pipe wall under the long-term high-speed fluid erosion, and even serious wear phenomena such as perforation. For this reason, we propose a wear-resistant variable-diameter oil pipe for oil production wells. Summary of the Invention

[0004] The present invention provides a wear-resistant variable-diameter oil pipe for oil production wells, which solves the technical problem in the related art that the pipe wall gradually thins under the long-term high-speed fluid erosion, and even serious wear phenomena such as perforation occur.

[0005] The present invention provides a wear-resistant variable-diameter oil pipe for oil production wells, including: a variable-diameter joint connecting adjacent oil pipes, which is internally provided with a friction-reducing and flow-splitting mechanism;

[0006] The friction-reducing and flow-splitting mechanism is composed of a flow-splitting inner pipe and an aperture adjusting component. Among them, a plurality of optical fiber sensors are arranged between the flow-splitting inner pipe and the liquid inlet end of the variable-diameter joint. The aperture adjusting component includes a flexible inner wall film, a double-shrinking core, and a tension spring component. The double-shrinking core is respectively embedded in the liquid inlet end and the liquid outlet end of the flexible inner wall film in a spring shape, and the adjacent ends are elastically connected through the tension spring component;

[0007] The optical fiber sensors collect liquid pressure and flow velocity parameters in real time and transmit them to the intelligent control system. This system synchronously changes the pitches of the first shrinking core and the second shrinking core of the double-shrinking core by regulating the tension of the tension spring component, so that the fluid forms a differential swirl layer between the flexible inner wall film and the flow-splitting inner pipe, reduces the direct contact wear of the pipe wall by using the flow velocity gradient, and simultaneously realizes the dynamic adjustment of the flow rate based on pressure feedback.

[0008] Further, the shunt inner tube is divided into three sections, namely the middle section of the inner tube, the bottom section of the inner tube, and the top section of the inner tube. The variable-diameter joint is divided into three sections, namely the middle section of the joint, the bottom section of the joint, and the top section of the joint. The shunt inner tube and the variable-diameter joint are coaxial.

[0009] Further, the inner walls of the bottom section of the inner tube and the top section of the inner tube are respectively provided with bottom-section guiding threads and top-section guiding threads. The thread directions of the bottom-section guiding threads and the top-section guiding threads are the same, and the thread directions of the bottom-section guiding threads and the top-section guiding threads are opposite to the thread direction of the double-shrinking core.

[0010] Further, a plurality of connecting columns are evenly distributed along the circumferential direction in the annular gap between the outer wall of the bottom section of the inner tube and the inner wall of the variable-diameter joint. The plurality of connecting columns are all in the shape of triangular prisms. The fiber optic sensors are fixedly embedded in the connecting columns. The plurality of fiber optic sensors correspond to the plurality of connecting columns one by one. The fiber optic sensors are in contact with the liquid entering the variable-diameter joint.

[0011] Further, a wire passing hole is provided in the barrel wall of the variable-diameter joint. A master control wire is passed through the wire passing hole. One end of the master control wire is connected to the fiber optic sensor, and the other end of the master control wire passes through the outer wall of the variable-diameter joint and is connected to the data line in other oil pipes. At the same time, the data line is connected to the intelligent control system on the ground.

[0012] Further, the double-shrinking core includes a first shrinking core and a second shrinking core. The first shrinking core is located inside the bottom section of the joint, and one end of the first shrinking core close to the liquid inlet end of the variable-diameter joint is fixedly connected to the inner wall of the bottom section of the joint.

[0013] Further, the second shrinking core is located inside the top section of the joint, and one end of the second shrinking core close to the liquid outlet end of the variable-diameter joint is fixedly connected to the inner wall of the top section of the joint. The adjacent ends of the first shrinking core and the second shrinking core are connected to a spring member. The spring member is located inside the middle section of the joint, and the spring member is fixedly connected to the inner wall of the middle section of the joint.

[0014] Further, both ends of the flexible inner wall membrane are fixedly connected to the top section of the joint and the bottom section of the joint respectively, and the flexible inner wall membrane completely surrounds the first shrinking core and the second shrinking core. A binding band ring is arranged between the thread seams of the first shrinking core and the second shrinking core, and the inner and outer walls of the binding band ring are respectively fixedly connected to the variable-diameter joint and the flexible inner wall membrane.

[0015] Further, the spring member includes a pulling and receiving outer cylinder. A pulling and receiving inner cylinder is fixedly arranged inside the pulling and receiving outer cylinder. The inner part of the pulling and receiving inner cylinder is divided into two spaces. A piston member is slidably arranged in each of the two spaces. Piston columns are arranged on both piston members, and the top ends of the two piston columns are respectively fixedly connected to the first shrinking core and the second shrinking core.

[0016] Furthermore, air intake holes are provided at the air intake ends of the two spaces inside the retractable inner cylinder, and a ventilation pipe is provided at the air intake end of the retractable outer cylinder. The other end passes through the outer wall of the reducing joint and is connected to the air pipe in other oil pipes.

[0017] The beneficial effects of the present invention are as follows:

[0018] By providing a friction-reducing and flow-splitting mechanism inside the reducing joint, the present invention effectively reduces the wear of the oil pipe and extends its service life. The optical fiber sensor arranged between the flow-splitting inner pipe and the liquid inlet end of the reducing joint can collect the pressure and flow rate parameters of the liquid in real time and transmit the data to the intelligent control system. According to these data, the system synchronously changes the pitch of the double retractable core by adjusting the tension of the tension spring member, so that a differential swirl layer is formed between the flexible inner wall film and the flow-splitting inner pipe. This differential swirl layer uses the flow rate gradient to reduce the direct contact between the fluid and the pipe wall, thereby significantly reducing wear;

[0019] Through the pressure feedback closed-loop control system, the dynamic regulation of the flow rate and the intelligent balance of the wellbore pressure are realized. The variable pitch design of the aperture adjustment component can automatically adjust the flow area according to the formation liquid supply capacity, reducing energy loss while maintaining production capacity. When the bottom hole pressure fluctuates, the system can complete parameter adjustment within 0.5 seconds, improving the liquid production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is the overall structural schematic diagram of the present invention;

[0021] Figure 2 is the connection structural schematic diagram of the reducing joint of the present invention;

[0022] Figure 3 is the internal structural schematic diagram of the reducing joint of the present invention;

[0023] Figure 4 is of the present invention Figure 3 magnified schematic diagram at position A in;

[0024] Figure 5 is the structural schematic diagram of the second retractable core position of the present invention;

[0025] Figure 6 is the internal structural schematic diagram of the flow-splitting inner pipe of the present invention;

[0026] Figure 7 is the connection structural schematic diagram of the first retractable core and the second retractable core of the present invention;

[0027] Figure 8 is the structural schematic diagram of the retractable outer cylinder of the present invention;

[0028] Figure 9 is the internal structural schematic diagram of the retractable outer cylinder of the present invention.

[0029] In the figure: 1 is a reducing joint; 11 is the middle section of the joint; 12 is the bottom section of the joint; 13 is the top section of the joint; 2 is an anti-friction flow splitting mechanism; 201 is the flow splitting inner tube; 21 is the middle section of the inner tube; 22 is the bottom section of the inner tube; 23 is the top section of the inner tube; 24 is a connecting column; 25 is an optical fiber sensor; 26 is the main control line; 27 is a wire passing hole; 28 is the bottom section diversion thread; 29 is the top section diversion thread; 3 is an aperture adjusting assembly; 31 is a flexible inner wall film; 32 is the first shrinking core; 33 is the second shrinking core; 34 is a pulling and receiving outer cylinder; 35 is a ventilation pipe; 36 is a pulling and receiving inner cylinder; 37 is an air inlet hole; 38 is a piston part; 39 is a piston column; 301 is a binding strap ring. Specific implementation mode

[0030] Now, the subject matter described herein will be discussed with reference to exemplary embodiments. It should be understood that discussing these embodiments is only to enable those skilled in the art to better understand and thus implement the subject matter described herein. Without departing from the scope of protection of the content of this specification, changes can be made to the functions and arrangements of the elements discussed. Each example can omit, substitute, or add various processes or components as needed. Additionally, the features described relative to some examples can also be combined in other examples.

[0031] As Figure 1 , Figure 2 , Figure 3 and Figure 7 shown, an anti-wear variable-diameter oil production well tubing includes: a reducing joint 1 for connecting adjacent tubing, and an anti-friction flow splitting mechanism 2 is provided therein;

[0032] The anti-friction flow splitting mechanism 2 is composed of a flow splitting inner tube 201 and an aperture adjusting assembly 3. Among them, a plurality of optical fiber sensors 25 are arranged between the flow splitting inner tube 201 and the liquid inlet end of the reducing joint 1. The aperture adjusting assembly 3 includes a flexible inner wall film 31, a double shrinking core and a spring member. The double shrinking core is respectively embedded in the liquid inlet end and the liquid outlet end of the flexible inner wall film 31 in a spring shape, and the adjacent ends are elastically connected by the spring member;

[0033] The optical fiber sensors 25 collect liquid pressure and flow rate parameters in real time and transmit them to the intelligent control system. This system synchronously changes the pitches of the first shrinking core 32 and the second shrinking core 33 of the double shrinking core by adjusting the tension of the spring member, so that a differential swirl layer is formed between the flexible inner wall film 31 and the flow splitting inner tube 201 for the fluid, and the direct contact wear of the pipe wall is reduced by using the flow rate gradient, and at the same time, the dynamic adjustment of the flow rate based on pressure feedback is realized.

[0034] The flow splitting inner tube 201 is divided into three sections, namely the middle section 21 of the inner tube, the bottom section 22 of the inner tube, and the top section 23 of the inner tube. The reducing joint 1 is divided into three sections, namely the middle section 11 of the joint, the bottom section 12 of the joint, and the top section 13 of the joint. The flow splitting inner tube 201 and the reducing joint 1 are coaxial.

[0035] The inner walls of the bottom section 22 and the top section 23 of the inner pipe are respectively provided with a bottom-section flow-guiding thread 28 and a top-section flow-guiding thread 29. The thread directions of the bottom-section flow-guiding thread 28 and the top-section flow-guiding thread 29 are the same, and the thread directions of the bottom-section flow-guiding thread 28 and the top-section flow-guiding thread 29 are opposite to the thread direction of the double-shrinking core.

[0036] As Figure 4 、 Figure 5 、 Figure 6 and Figure 8 shown, a plurality of connecting columns 24 are evenly distributed circumferentially in the annular gap between the outer wall of the bottom section 22 of the inner pipe and the inner wall of the reducing joint 1. The plurality of connecting columns 24 are all in the shape of triangular prisms. The fiber optic sensors 25 are fixedly embedded in the connecting columns 24. The plurality of fiber optic sensors 25 correspond to the plurality of connecting columns 24 one by one. The fiber optic sensors 25 are in contact with the liquid entering the reducing joint 1.

[0037] A wire passing hole 27 is formed in the barrel wall of the reducing joint 1. A master control wire 26 is passed through the wire passing hole 27. One end of the master control wire 26 is connected to the fiber optic sensor 25, and the other end of the master control wire 26 passes through the outer wall of the reducing joint 1 and is connected to the data line in other oil pipes. At the same time, the data line is connected to the intelligent control system on the ground.

[0038] The double-shrinking core includes a shrinking core one 32 and a shrinking core two 33. The shrinking core one 32 is located inside the bottom section 12 of the joint, and one end of the shrinking core one 32 close to the liquid inlet end of the reducing joint 1 is fixedly connected to the inner wall of the bottom section 12 of the joint.

[0039] The shrinking core two 33 is located inside the top section 13 of the joint, and one end of the shrinking core two 33 close to the liquid outlet end of the reducing joint 1 is fixedly connected to the inner wall of the top section 13 of the joint. The adjacent ends of the shrinking core one 32 and the shrinking core two 33 are connected to a spring member. The spring member is located inside the middle section 11 of the joint, and the spring member is fixedly connected to the inner wall of the middle section 11 of the joint.

[0040] Both ends of the flexible inner wall film 31 are respectively fixedly connected to the top section 13 and the bottom section 12 of the joint, and the flexible inner wall film 31 completely surrounds the shrinking core one 32 and the shrinking core two 33. A binding band ring 301 is arranged between the thread seams of the shrinking core one 32 and the shrinking core two 33, and the inner and outer walls of the binding band ring 301 are respectively fixedly connected to the reducing joint 1 and the flexible inner wall film 31.

[0041] As Figure 7 、 Figure 8 and Figure 9As shown, the tension spring member includes a retracting outer cylinder 34. Inside the retracting outer cylinder 34, a retracting inner cylinder 36 is fixedly arranged. The inside of the retracting inner cylinder 36 is divided into two spaces. In each of the two spaces, a piston member 38 is slidably arranged. On each of the two piston members 38, a piston column 39 is arranged, and the tops of the two piston columns 39 are fixedly connected to the first retracting core 32 and the second retracting core 33 respectively.

[0042] Inlet holes 37 are provided at the inlet ends of the two spaces inside the retracting inner cylinder 36. A ventilation pipe 35 is arranged at the inlet end of the retracting outer cylinder 34. The other end passes through the outer wall of the reducing joint 1 and is connected to the air pipe in other oil pipes.

[0043] During oil production operations, when the oil pipe is connected to the oil production well, the liquid in the reservoir flows upward through the oil pipe. The liquid first enters the liquid inlet end of the reducing joint 1. At this time, the friction-reducing and flow-splitting mechanism 2 starts to function.

[0044] After the liquid enters the flow-splitting inner pipe 201, a part of it flows upward along the flow-splitting inner pipe 201, and the other part flows upward in the space between the flow-splitting inner pipe 201 and the flexible inner wall film 31. The inner walls of the bottom section 22 and the top section 23 of the inner pipe are respectively provided with bottom-section guiding threads 28 and top-section guiding threads 29, and their thread directions are the same, but opposite to the thread direction of the double retracting cores. This thread design can guide the liquid to form a rotational flow in a specific direction inside the flow-splitting inner pipe 201, which helps to adjust the flow state of the fluid, reduce the generation of turbulent flow and eddy current, and thus reduce the impact and wear on the pipe wall.

[0045] After receiving the data transmitted by the optical fiber sensor 25, the intelligent control system will, according to the current liquid pressure and flow rate conditions, synchronously change the pitch of the first retracting core 32 and the second retracting core 33 of the double retracting cores by regulating the tension of the tension spring member. By controlling the external air supply air pump, the gas flows into the gap between the retracting outer cylinder 34 and the retracting inner cylinder 36 through the ventilation pipe 35, and then enters the two spaces in the retracting inner cylinder 36 through the inlet holes 37. As the air pressure changes, the two piston members 38 are pushed to slide, so as to push or pull back the first retracting core 32 and the second retracting core 33 through the piston columns 39. When the first retracting core 32 and the second retracting core 33 are stretched, the pitch of the thread formed by the flexible inner wall film 31 will increase, on the one hand, adjusting the flow rate of the liquid, and on the other hand, increasing the flow space of the liquid.

[0046] Through this adjustment of the pitch, a differential swirling flow layer is formed between the flexible inner wall membrane 31 and the flow-dividing inner tube 201. The formation of the differential swirling flow layer utilizes the principle of velocity gradient, that is, there is a velocity difference between fluid layers with different flow velocities, thus forming a relatively low-velocity fluid buffer layer near the pipe wall, reducing the situation of high-speed fluid directly impacting the pipe wall, and further reducing the direct contact wear of the pipe wall. At the same time, the dynamic flow regulation function based on pressure feedback is realized. When the liquid pressure changes, the intelligent control system can timely adjust the pitch of the double-shrinking core, change the fluid flow channel and flow state, so as to realize the dynamic regulation of the flow rate and ensure the stability and efficiency of the oil production process.

[0047] Both the flow-dividing inner tube 201 and the reduced-diameter joint 1 adopt a three-segment segmentation and are coaxially arranged. This enables the liquid to smoothly transition between each segment during the flow process, avoiding fluid turbulence and vortex phenomena caused by sudden changes in pipe diameter or axis offset. In actual oil production operations, this smooth flow state can significantly reduce the impact force of the liquid on the pipe wall and reduce mechanical wear. At the same time, the segmented design facilitates precise flow control and pressure regulation in oil layers at different depths, improving the flexibility and adaptability of oil production. For example, in deep well oil production, the pressure and temperature differences in oil layers at different depths are relatively large. Through the segmented design, it is possible to optimize and adjust according to the specific conditions of each segment, improving the oil production efficiency.

[0048] The fiber optic sensor 25 can collect the pressure and flow rate parameters of the liquid in real time, providing accurate data support for the intelligent control system. This real-time monitoring and feedback mechanism enables the system to quickly respond to various changes in the oil production process, such as oil layer pressure fluctuations, fluid property changes, etc. The intelligent control system adjusts the pitch of the double-shrinking core by controlling the tension of the spring member according to these real-time data, realizing the dynamic optimization of the fluid flow state. In practical applications, it can effectively avoid problems such as increased pipe wall wear and unstable flow rate caused by parameter changes, improving the reliability and stability of the oil production system.

[0049] The double-shrinking core design enables the flexible inner wall membrane 31 to form an inner wall structure with specific threads under the support of the double-shrinking core and the elastic action of the spring member. When the intelligent control system adjusts the tension of the spring member, the pitch of the double-shrinking core changes, and then the thread form of the flexible inner wall membrane 31 is changed, affecting the flow velocity and flow space of the fluid. During the oil production process, this synergistic effect can flexibly adjust the fluid flow state according to actual needs, form a differential swirling flow layer, reduce pipe wall wear, and at the same time realize the dynamic flow regulation based on pressure feedback. For example, in the case of a relatively high oil layer pressure, by increasing the pitch, increasing the fluid flow space, reducing the flow velocity, and reducing wear; while when the pressure is low, reducing the pitch, increasing the flow velocity, and ensuring the oil production efficiency.

[0050] The thread design can guide the fluid to form a rotational flow in a specific direction within the shunt inner pipe 201, which helps to adjust the flow state of the fluid, reduce the generation of turbulence and eddy currents. In actual oil production, this orderly rotational flow can reduce the impact force of the fluid on the pipe wall, reduce wear, and at the same time improve the flow stability of the fluid, which is beneficial to improving oil production efficiency and reducing energy consumption.

[0051] This layout enables the fiber optic sensors 25 to be evenly distributed around the annular gap, comprehensively monitoring the pressure and flow rate parameters of the liquid and avoiding monitoring blind spots. At the same time, the triangular prism-shaped connecting column 24 has good structural strength and stability, which can protect the fiber optic sensors 25 from liquid impact and mechanical damage, ensuring the accuracy and reliability of the monitoring data.

[0052] Gas is introduced through an external air supply air pump to achieve the adjustment of the double-shrinking core pitch. This pneumatic control method has the advantages of fast response speed, high control precision, and stable power transmission. In oil production operations, it can quickly adjust the fluid flow state according to the instructions of the intelligent control system to meet the requirements of real-time adjustment. At the same time, pneumatic control avoids complex mechanical transmission structures, reduces the failure rate, and improves the reliability and maintenance convenience of the system.

[0053] When the sand-containing crude oil enters the reducing joint 1, natural shunting of the fluid occurs at the inlet of the shunt inner pipe 201. According to Bernoulli's equation, approximately 55% - 65% of the high-pressure fluid enters the internal channel of the shunt inner pipe 201, and the remaining 35% - 45% of the fluid enters the annular gap formed by the shunt inner pipe 201 and the flexible inner wall film 31. The designed gap width is 8 - 12 mm.

[0054] The fluid generates a counterclockwise swirl under the action of the bottom-section guiding threads 28 and the top-section guiding threads 29, with a rotational speed of approximately 1200 - 1800 rpm. The guiding threads are designed with a 30° helix angle, and the guiding efficiency is increased to 82%.

[0055] The surface of the flexible inner wall film 31 forms a clockwise swirl due to the thread support of the double-shrinking core, with a rotational speed of approximately 800 - 1200 rpm. The two reverse swirls form a velocity gradient layer at the contact surface, with a thickness of approximately 2 - 5 mm.

[0056] Through the synergistic effect of the double-shrinking core and the guiding threads, a Taylor vortex structure is formed in the annular gap, indicating that this structure can reduce the sand particle concentration gradient by 42%. Through the combination of threads with opposite rotation directions, a stable Taylor vortex structure is formed in the annular gap. This structure improves the uniformity of sand particle distribution by 65% and reduces the wall impact load by 48%. At a flow rate of 10 m / s, the sand particle impact energy in the traditional straight pipe section is 28.4 J / m², while in the system of the present invention, it is reduced to 6.3 J / m².

[0057] Based on the pressure and flow rate coupling algorithm, the pitch is continuously adjusted from 0.2 to 3.5 mm through the tension spring, and the response speed is increased to <80 ms.

[0058] Using a fiber Bragg grating sensor with a high temperature resistance of 150 °C, the pressure measurement accuracy of 0 - 30 MPa is ±0.3% FS, and the flow rate measurement error is less than 1.2%.

[0059] The above describes the embodiments of the present invention, but the present invention is not limited to the above specific embodiments. The above specific embodiments are merely illustrative and not restrictive. Under the inspiration of this embodiment, those of ordinary skill in the art can also make many forms, all of which fall within the protection scope of this embodiment.

Claims

1. A wear-resistant variable diameter oil pipe for oil production wells, characterized in that: include: A reducer (1) connecting adjacent oil pipes, wherein a friction-reducing flow-dividing mechanism (2) is provided therein; The friction-reducing flow-dividing mechanism (2) is composed of a flow-dividing inner tube (201) and an aperture adjustment component (3), wherein a plurality of optical fiber sensors (25) are arranged between the flow-dividing inner tube (201) and the liquid inlet end of the reducer (1), and the aperture adjustment component (3) comprises a flexible inner wall membrane (31), a double shrinkable core and a tension spring component, wherein the double shrinkable core is respectively embedded in the liquid inlet end and the liquid outlet end of the flexible inner wall membrane (31) in a spring shape, and adjacent ends are elastically connected via the tension spring component; The optical fiber sensor (25) collects liquid pressure and flow rate parameters in real time and transmits them to an intelligent control system. The system adjusts the tension of the tension spring to synchronously change the pitch of the contraction core 1 (32) and the contraction core 2 (33) of the double contraction core, so that the fluid forms a differential swirl layer between the flexible inner wall membrane (31) and the diversion inner tube (201), and uses the flow rate gradient to reduce direct contact wear of the tube wall, while realizing dynamic flow regulation based on pressure feedback.

2. The wear-resistant variable diameter oil pipe for oil wells according to claim 1, characterized in that: The flow-dividing inner tube (201) is divided into three sections, namely, an inner tube middle section (21), an inner tube bottom section (22) and an inner tube top section (23); the reducing joint (1) is divided into three sections, namely, a joint middle section (11), a joint bottom section (12) and a joint top section (13); the flow-dividing inner tube (201) is coaxial with the reducing joint (1).

3. The wear-resistant variable diameter oil pipe for oil wells according to claim 2, characterized in that: The inner walls of the inner tube bottom section (22) and the inner tube top section (23) are respectively provided with bottom section flow guiding threads (28) and top section flow guiding threads (29); the thread directions of the bottom section flow guiding threads (28) and the top section flow guiding threads (29) are the same, and the thread directions of the bottom section flow guiding threads (28) and the top section flow guiding threads (29) are opposite to the thread directions of the double shrink core.

4. The wear-resistant variable diameter oil pipe for oil production wells according to claim 2, characterized in that: A plurality of connecting columns (24) are evenly distributed along the circumferential direction in the annular gap between the outer wall of the inner tube bottom section (22) and the inner wall of the reducer (1); the plurality of connecting columns (24) are all in the shape of triangular prisms; the optical fiber sensors (25) are fixedly embedded in the connecting columns (24); the plurality of optical fiber sensors (25) correspond one-to-one to the plurality of connecting columns (24); and the optical fiber sensors (25) are in contact with liquid entering the reducer (1).

5. The wear-resistant variable diameter oil pipe for oil production wells according to claim 4, characterized in that: A wire passing hole (27) is provided in the wall of the reducer (1), a master control line (26) is passed through the wire passing hole (27), one end of the master control line (26) is connected to the optical fiber sensor (25), and the other end of the master control line (26) passes through the outer wall of the reducer (1) and is connected to data lines in other oil pipes, and the data line is connected to a ground intelligent control system.

6. The wear-resistant variable diameter oil pipe for oil production wells according to claim 2, characterized in that: The double shrink core comprises a shrink core 1 (32) and a shrink core 2 (33), wherein the shrink core 1 (32) is located on the inner side of the joint bottom section (12), and an end of the shrink core 1 (32) close to the liquid inlet end of the reducer (1) is fixedly connected to the inner wall of the joint bottom section (12).

7. The wear-resistant variable diameter oil pipe for oil production wells according to claim 6, characterized in that: The shrinkable core 2 (33) is located on the inner side of the joint top section (13), and one end of the shrinkable core 2 (33) close to the liquid outlet end of the reducer (1) is fixedly connected to the inner wall of the joint top section (13); the shrinkable core 1 (32) and the shrinkable core 2 (33) are connected to a tension spring component, and the tension spring component is located on the inner side of the joint middle section (11), and the tension spring component is fixedly connected to the inner wall of the joint middle section (11).

8. The wear-resistant variable diameter oil pipe for oil wells according to claim 1, characterized in that: The two ends of the flexible inner wall membrane (31) are respectively fixedly connected to the joint top section (13) and the joint bottom section (12), and the flexible inner wall membrane (31) fully surrounds the shrinkable core 1 (32) and the shrinkable core 2 (33). A binding belt ring (301) is provided between the threaded seams of the shrinkable core 1 (32) and the shrinkable core 2 (33), and the inner and outer walls of the binding belt ring (301) are respectively fixedly connected to the reducer (1) and the flexible inner wall membrane (31).

9. The wear-resistant variable diameter oil pipe for oil wells according to claim 1, characterized in that: The tension spring component comprises a tensioning outer tube (34), a tensioning inner tube (36) is fixedly arranged inside the tensioning outer tube (34), the interior of the tensioning inner tube (36) is divided into two spaces, a piston component (38) is slidably arranged in each of the two spaces, and a piston column (39) is arranged on each of the two piston components (38), and the top ends of the two piston columns (39) are fixedly connected to the shrinking core 1 (32) and the shrinking core 2 (33) respectively.

10. The wear-resistant variable diameter oil pipe for oil production wells according to claim 9, characterized in that: The air inlet ends of the two spaces inside the retracting inner cylinder (36) are provided with air inlet holes (37), and the air inlet end of the retracting outer cylinder (34) is provided with a vent pipe (35), the other end of which passes through the outer wall of the reducer (1) and is connected to the air pipe in the other oil pipe.

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